1. Field of the Invention
The present invention relates to a portable terminal, and more particular to a keypad assembly serving as an input device for a portable terminal.
2. Description of the Related Art
Generally, a portable terminal refers to an electronic device which allows a user to perform a voice or data communication or message transmission as well as a multimedia service, such as storage of various information, playing games, and watching video content. The portable electronic device has been manufactured in various forms including an electronic note, a palm Personal Computer (PC), a portable game player, a moving image/music file player, a cellular phone, a notebook PC, etc.
Recently, with integration of an electronic note or multimedia function into a mobile communication terminal such as a cellular phone, a user can now easily enjoy various multimedia services such as a banking service, a game/multimedia service, a simple office work and the like as well as the traditional communication function.
Although a typical mobile communication terminal can perform voice communication or short message generation with a conventional keypad including keys for inputting numbers, send/end keys, a menu key, and a shift key, a need for expanding the keypad to serve more functions is increasing with integration of various functions into the mobile communication terminal. To this end, additional keys may be mounted by reducing the size of each key, but the size reduction of the key may cause input errors. For this reason, a terminal having a QWERTY keypad has emerged in which two housings are coupled and the keypad can be manipulated by positioning the terminal in a horizontal orientation during operation.
Meanwhile, it is difficult to secure a sufficiently large keypad area while minimizing the size of a terminal in terms of portability.
FIGS. 1 through 3 are views showing a portable terminal 100 including a keypad assembly 102 according to an embodiment of the prior art. As shown in FIGS. 1 through 3, the keypad assembly 102 according to an embodiment of the prior art comprises a plurality of key tops 121 on a top surface thereof and is disposed between a front case 101a and a rear case 101b, defining a housing 101 of the portable terminal 100. The front case 101a includes an opening 111 which exposes the keypad assembly 102, more specifically, the key tops 121, and a window 113 for installing a display device (not shown).
The circumference of the opening 111 is in the form of a frame which fixes the keypad assembly 102 within the housing 101 by enclosing the edge of the keypad assembly 102. In an inner side of the front case 101a, fixing protrusions 115 are formed along the circumference of the opening 111. The fixing protrusions 115 extend from the inner side of the front case 101a toward the rear case 101b. 
Binding ribs 127 extend from the edge of the keypad assembly 102, more specifically, from the edge of an inner side end of the key tops 121, and binding holes 129 are formed in the binding ribs 127. When the front case 101a is assembled to the rear case 101b on which the keypad assembly 102 is disposed, the fixing protrusions 115 are bound by passing through the engagement holes 129. Hence, the keypad assembly 102 is assembled to be in a predetermined position with respect to the front case 101a, thus being disposed within the opening 111.
In the conventional keypad assembly installation structure described above, when the keypad assembly 102 is installed, it is difficult to sufficiently utilize the area of the front case 101a, particularly, the width of the front case 101a. Referring to FIG. 3, the key tops 121 cannot be disposed on portions D of both side ends of the front case 101a and an available overall width W on which the key tops 121 can be disposed is limited by the portions D of the both side ends of the front case 101a. This is because the area covered by the portions D is used for forming the fixing protrusions 115 for fixing the keypad assembly 102 and for receiving the binding ribs 127 formed on the keypad assembly 102. Therefore, the conventional keypad assembly installation structure has a restriction in securing a wider area for display which is also a drawback in miniaturizing the terminal.